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AMERICAN BAR ASSOCIATION
ADOPTED BY THE HOUSE OF DELEGATES
FEBRUARY 6, 2012
RESOLUTION
RESOLVED, That the American Bar Association urges judges and lawyers to consider the
following factors in determining the manner in which expert testimony should be presented to a
jury and in instructing the jury in its evaluation of expert scientific testimony in criminal and
delinquency proceedings:
1.
2.
3.
4.
5.
6.
7.
Whether experts can identify and explain the theoretical and factual basis for any
opinion given in their testimony and the reasoning upon which the opinion is
based.
Whether experts use clear and consistent terminology in presenting their opinions.
Whether experts present their testimony in a manner that accurately and fairly
conveys the significance of their conclusions, including any relevant limitations of
the methodology used.
Whether experts explain the reliability of evidence and fairly address problems
with evidence including relevant evidence of laboratory error, contamination, or
sample mishandling.
Whether expert testimony of individuality or uniqueness is based on valid scientific
research.
Whether the court should prohibit the parties from tendering witnesses as experts
and should refrain from declaring witnesses to be experts in the presence of the
jury.
Whether to include in jury instructions additional specific factors that might be especially
important to a jury’s ability to fairly assess the reliability of and weight to be given expert
testimony on particular issues in the case.
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REPORT
The criminal justice system requires an integrated system of forensic science and the
The National Academy of Sciences (NAS) Report2 on forensic science, which was issued
in 2009, raised numerous issues about the presentation of expert testimony at trial. These issues
are significant. As the Supreme Court reminded us in Daubert: “Expert evidence can be both
powerful and quite misleading because of the difficulty in evaluating it.”3 The NAS Report
highlighted the limitations and failings of our criminal justice system with respect to forensic
science testimony and evidence. The need for reform and opportunities for change, however, are
not confined to the laboratories and are not limited to the work of forensic scientists. The trial
attorneys must approach forensic science evidence with better education, skill, and knowledge
than they have demonstrated in the past. Judges and juries cannot properly assess the weight of
the forensic science evidence if attorneys do not adequately investigate and present such
evidence. In any complex case involving contested forensic science issues or case where the
contested forensic science issues are difficult to comprehend, the parties and the court should be
encouraged to find innovative solutions to facilitate jury understanding, such as accommodations
in the trial structure to permit expert witnesses from both sides to testify sequentially or
permitting jurors to actively participate in questioning the expert witnesses.
law.1
Many of the reported problems with forensic science evidence have resulted from the
failures of trial attorneys to investigate thoroughly forensic science evidence, the
misunderstandings of trial attorneys concerning the nature of that evidence and misstatements by
trial attorneys concerning the weight to be attributed to that evidence. Until an elevation in the
knowledge base of trial attorneys is achieved,4 the adversarial system will continue to falter with
respect to the proper presentation of forensic science evidence.
In investigating, assessing, and presenting forensic science evidence, attorneys should
consider the following:
- The extent to which a particular forensic science discipline is founded on reliable
scientific methodology that gives it the capacity to accurately analyze evidence and report
findings;
- The extent to which examiners in a particular forensic science discipline rely on human
interpretation; and
1
This resolution was developed by a Forensic Science Task Force whose membership includes:
Professor Myrna S. Raeder (Co-chair), Matthew F. Redle (Co-chair), Barry A.J. Fisher (retired lab
director), Judge Ronald S. Reinstein, Betty Layne DesPortes, and Professor Paul G. Giannelli.
2
NATIONAL RESEARCH COUNCIL, NATIONAL ACADEMY OF SCIENCES, STRENGTHENING FORENSIC
SCIENCE IN THE UNITED STATES: A PATH FORWARD (2009) [hereinafter NAS FORENSIC SCIENCE REPORT].
3
Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579, 595 (1993) (quoting Jack B. Weinstein, Rule
702 of the Federal Rules of Evidence Is Sound: It Should Not Be Amended, 138 F.R.D. 631, 632 (1991)).
4
See ABA House of Delegates Recommendation 100E Adopted August 9-10, 2010, Item 10 (need
for forensic science training for lawyers and judges).
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- The extent to which the examiner using the particular forensic science technique in the
case followed established procedures and standards in examining the evidence.
By keeping these considerations in mind during the investigation and presentation of
forensic science evidence, attorneys will better inform the jury of the relevant contested forensic
science issues in the case. The evidence presented relevant to these considerations will also
provide the underlying basis for instructions to the jury concerning the relevant forensic science
issues.
1.
Basis and Reasoning for Expert Opinion
This provision tracks the ABA Standards on DNA Evidence5 and extends it to other
forensic disciplines.
2.
Clear and Consistent Terminology
The NAS Report on forensic science voiced concern about the use of terms such as
“match,” “consistent with,” “identical,” “similar in all respects tested,” and “cannot be excluded
as the source of.” These terms can have “a profound effect on how the trier of fact in a criminal
or civil matter perceives and evaluates scientific evidence.”6 Such terms need to be defined and
standardized, according to the Report. Moreover, ABA Resolution 100E(4) recommends: “the
development and adoption of standards and common terminology for the clear communication of
scientific testing results including, wherever possible, uniform report content within disciplines.”
3.
Accurate and Fair Testimony; Limitations of Technique
This provision tracks the ABA Standards on DNA Evidence7 and extends it to other
forensic disciplines. It also adds a phrase on the limitations of a technique. The NAS Report
recommended that a technique’s limitations be acknowledged in both court testimony and
laboratory reports.8
Microscopic hair analysis illustrates the importance of this point. In Williamson v.
Reynolds,9 a federal habeas corpus case, an expert testified at trial that hair samples were
“consistent microscopically.”10 What does the term “microscopically indistinguishable” or
“consistent with” mean? The probative value of this conclusion would, of course, vary if only a
hundred people had microscopically indistinguishable hair as opposed to several million. As one
hair examiner wrote: “If a pubic hair from the scene of a crime is found to be similar to those
5
ABA STANDARDS FOR CRIMINAL JUSTICE, DNA EVIDENCE, Standard 16-5.3(a) (3d ed. 2007)
[hereinafter DNA EVIDENCE].
6
NAS FORENSIC SCIENCE REPORT, supra note 2, at 21.
7
DNA EVIDENCE, supra note 5, Standard 16-5.3(b).
8
Id. at 21-22.
9
Williamson v. Reynolds, 904 F. Supp. 1529, 1558 (E.D. Okl. 1995), rev’d sub nom. on this
ground, Williamson v. Ward, 110 F.3d 1508, 1523 (10th Cir. 1997).
10
Id.
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from a known source, [the courts] do not know whether the chances that it could have originated
from another source are one in two or one in a billion.”11 In sum, the evidence may have little
probative value, and yet the jury might not appreciate this fact.12
This problem was exacerbated in Williamson because the expert went on to explain: “In
other words, hairs are not an absolute identification, but they either came from this individual or
there is—could be another individual somewhere in the world that would have the same
characteristics to their hair.”13 This is a gross overstatement. If it were true, hair evidence would
be nearly on a par with nuclear DNA profiling. It is not. In final argument, the prosecutor
proclaimed: “[T]here’s a match.”14 Even the state appellate court misunderstood the testimony,
writing that the “hair evidence placed [petitioner] at the decedent’s apartment.”15 Moreover, one
study found that the traditional adversary procedures—cross-examination, the presentation of
opposing experts, and jury instructions—do not cure the problem.16
Failure to clearly state the limitations of a technique can have serious consequences, as
suggested by the role that microscopic hair analysis played in many of the wrongful conviction
cases. A 1996 Department of Justice report discussing the exonerations of the first twenty-eight
convicts through the use of DNA technology highlighted the significant role that hair analysis
played in a number of these miscarriages of justice, including some death penalty cases. 17 Two
years later, a Canadian judicial inquiry into the wrongful conviction of Guy Paul Morin was
released. His original conviction was based, in part, on hair evidence. The judge conducting the
inquiry recommended that “[t]rial judges should undertake a more critical analysis of the
admissibility of hair comparison evidence as circumstantial evidence of guilt.”18 A 2008 study
of 200 DNA exoneration cases reported that hair testimony had been presented in forty-three of
the original trials.19 A subsequent examination of 137 trial transcripts in exoneration cases
concluded: “Sixty-five of the trials examined involved microscopic hair comparison analysis.
Of those, 25—or 38%—had invalid hair comparison testimony. Most (18) of these cases
11
B.D. Gaudette, Probabilities and Human Pubic Hair Comparisons, 21 J. FORENSIC SCI. 514, 514
(1976).
See United States v. Frazier, 387 F.3d 1244, 1263 (11th Cir. 2004) (“[E]xpert testimony may be
assigned talismanic significance in the eyes of lay jurors, and, therefore, the district courts must take care
to weigh the value of such evidence against its potential to mislead or confuse.”).
13
Williamson, 904 F. Supp. at 1554 (emphasis added).
14
Id. at 1557.
15
Williamson v. State, 812 P.2d 384, 397 (Okla. Crim. App. 1991).
16
See Dawn McQuiston-Surrett & Michael J. Saks, The Testimony of Forensic Identification
Science: What Expert Witnesses Say and What Factfinders Hear, 33 LAW & HUM. BEHAV. 436, 451 (2009)
(“These results should give pause to anyone who believes that the traditional tools of the adversarial
process (e.g., cross-examination, opposing experts, instructions) will readily undo the effects of
misleading expert testimony.”).
17
EDWARD CONNORS ET AL., CONVICTED BY JURIES, EXONERATED BY SCIENCE: CASE STUDIES IN THE
USE OF DNA EVIDENCE TO ESTABLISH INNOCENCE AFTER TRIAL (1996), available at
http://www.ncjrs.gov/pdffiles/dnaevid.pdf [hereinafter Exonerated by Science].
18
HON. FRED KAUFMAN, THE COMMISSION ON PROCEEDINGS INVOLVING GUY PAUL MORIN (Ontario
Ministry of the Attorney General 1998) (Recommendation 2), available at
http://www.attorneygeneral.jus.gov.on.ca/english/about/pubs/morin/.
19
Brandon L. Garrett, Judging Innocence, 108 COLUM. L. REV. 55, 81 (2008).
12
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involved invalid individualizing claims.”20
Overstatements
The NAS Report also criticized exaggerated testimony such as claims of perfect
accuracy, infallibility, or a zero error rate: “[I]mprecise or exaggerated expert testimony has
sometimes contributed to the admission of erroneous or misleading evidence.”21
“Zero Error Rate”
For example, in United States v. Havvard,22 which involved a Daubert challenge to
fingerprint evidence, the expert claimed the “error rate for the method is zero.”23 Note the word
method in the above quote. Examiners argued that, while individual examiners may make
mistakes, the methodology itself is perfect. However, the dichotomy between “methodological”
and “human” error rates in this context is “practically meaningless”24 because the examiner is the
method.25
The NAS Report addressed this point: “Although there is limited information about the
accuracy and reliability of friction ridge analyses, claims that these analyses have zero error rates
are not scientifically plausible.”26 The Report goes on to comment: “Some in the latent print
community argue that the method itself, if followed correctly . . . has a zero error rate. Clearly,
this assertion is unrealistic . . . . The method, and the performance of those who use it, are
inextricably linked, and both involve multiple sources of error (e.g., errors in executing the
process steps, as well as errors in human judgment.)”27
Several courts have also commented on this issue. For example, in United States v.
Mitchell,28 the Third Circuit commented: “Testimony at the Daubert hearing indicated that some
latent fingerprint examiners insist that there is no error rate associated with their activities . . . .
This would be out-of-place under Rule 702.”29 The same issue arose in a firearms identification
case. In United States v. Glynn,30 the court wrote that “[t]he problem is compounded by the
20
Brandon L. Garrett & Peter J. Neufeld, Invalid Forensic Science Testimony and Wrongful
Convictions, 95 VA. L. REV. 1, 47 (2009).
21
NAS FORENSIC SCIENCE REPORT, supra note 2, at 4.
22
117 F. Supp. 2d 848 (S.D. Ind. 2000), aff’d, 260 F.3d 597 (7th Cir. 2001).
23
Id. at 854.
24
See Jennifer L. Mnookin, Fingerprint Evidence in an Age of DNA Profiling, 67 BROOK. L. REV. 13,
60 (2001). See also Simon A. Cole, More Than Zero: Accounting for Error in Latent Fingerprint
Identification, 95 J. CRIM. L. & CRIMINOLOGY 985, 1040 (2005) (“in fingerprint practice the concept is
vacuous”).
25
See Sandy L. Zabell, Fingerprint Evidence, 13 J.L. & POL’Y 143, 172 (2005) (“But, given its
unavoidable subjective component, in latent print examination people are the process.”) (emphasis
added).
26
NAS FORENSIC SCIENCE REPORT, supra note 2, at 142.
27
Id. at 143.
28
365 F.3d 215 (3d Cir. 2004) (admitting fingerprint evidence).
29
Id. at 245-46.
30
578 F. Supp. 2d 567 (S.D.N.Y. 2008).
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tendency of ballistics experts . . . to make assertions that their matches are certain beyond all
doubt, that the error rate of their methodology is ‘zero,’ and other such pretensions.”31
“Hundred Percent Accurate”
In a different firearms identification case, United States v. Monteiro,32 the court noted
that:
The examiners testified to the effect that they could be 100 percent sure of a match.
Because an examiner’s bottom line opinion as to an identification is largely a subjective
one, there is no reliable statistical or scientific methodology which will currently permit
the expert to testify that it is a “match” to an absolute certainty, or to an arbitrary degree
of statistical certainty.33
The NAS Report concurred: “The insistence by some forensic practitioners that their disciplines
employ methodologies that have perfect accuracy and produce no errors has hampered efforts to
evaluate the usefulness of the forensic science disciplines.”34 In 2000, Stephen Bunch, an FBI
firearms identification expert, wrote:
[T]here is no rational or scientific ground for making claims of absolute certainty in any
of the traditional identification sciences, which include fingerprint, document, firearms,
toolmark, and shoe and tire-tread analysis. Case-specific conclusions of identity rest on a
fundamental proposition, or hypothesis; namely, that no two fingerprints, bullets, etc.,
from different sources will appear sufficiently similar to induce a competent forensic
examiner to posit a common source. But as any logician or philosopher of science would
insist, no hypothesis can be proved absolutely.35
In its first report on DNA profiling, the National Academy of Sciences report commented:
“Prosecutors and defense counsel should not oversell DNA evidence. Presentations that suggest
to a judge or jury that DNA typing is infallible are rarely justified and should be avoided.”36
“Scientific”
The use of terms such as “science” or “scientific” in presenting expert testimony may
also be problematic. In 1995, a federal district court in United States v. Starzecpyzel37 concluded
that “forensic document examination, despite the existence of a certification program,
professional journals and other trappings of science, cannot, after Daubert, be regarded as
‘scientific . . . knowledge.’”38 The court further stated that “while scientific principles may
31
Id. at 574.
407 F. Supp. 2d 351 (D. Mass. 2006).
33
Id. at 372 (emphasis added).
34
NAS FORENSIC SCIENCE REPORT, supra note 2, at 47.
35
Stephen G. Bunch, Consecutive Matching Striation Criteria: A General Critique, 45 J. FORENSIC
SCI. 955, 956 (2000).
36
NATIONAL RESEARCH COUNCIL, DNA TECHNOLOGY IN FORENSIC SCIENCE 26 (1992).
37
880 F. Supp. 1027 (S.D.N.Y. 1995).
38
Id. at 1038.
32
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relate to aspects of handwriting analysis, they have little or nothing to do with the day-to-day
tasks performed by [Forensic Document Examiners] . . . . [T]his attenuated relationship does not
transform the FDE into a scientist.”39
Although the court went on to admit the testimony as technical evidence, it placed
conditions on its admissibility.40 Because FDEs use terms such as “laboratory” and refer to
authorities with titles containing the words “science” or “scientific,” there is a risk, according to
the court, that jurors may bestow upon FDEs the aura of the infallibility of science.
Consequently, these terms should not be used in the expert’s testimony. Moreover, the court
approved a jury instruction, which stated that “FDEs offer practical, rather than scientific
expertise.”41 Similarly, in United States v. Glynn,42 a firearms identification case, the court
stated: “Based on the Daubert hearings this Court conducted . . . , the Court very quickly
concluded that whatever else ballistics identification analysis could be called, it could not fairly
be called ‘science.’”43
The NAS Report provides some support for this position: “The law’s greatest dilemma in
its heavy reliance on forensic evidence . . . concerns the question of whether—and to what
extent—there is science in any given forensic science discipline.”44 A subsequent passage
concludes: “Much forensic evidence—including, for example, bite marks and firearm and
toolmark identifications—is introduced in criminal trials without any meaningful scientific
validation, determination of error rates, or reliability testing to explain the limits of the
discipline.”45
Philosophers of science disagree about the definition of “science,”46 and the Supreme
Court in Kumho Tire rejected the distinction between science and technical evidence for
purposes of applying the Daubert test because such a distinction would be difficult to draw.47
Moreover, claiming the mantle of “science” is a two-edged sword. It may impress the jury, but it
also subjects the field to the rigors of the scientific method. The forensic identification
39
Id. at 1041.
In the court’s view, Daubert did not apply to nonscientific experts. The court relied on the
following statement in Daubert: “Our discussion is limited to the scientific context because that is the
nature of the expertise offered here.” 509 U.S. at 590 n.8. This position was undercut by Kumho Tire,
which held that all expert testimony must pass the Daubert reliability test. Kumho Tire Co., Ltd. v.
Carmichael, 526 U.S. 137, 149 (1999).
41
880 F. Supp. at 1049.
42
578 F. Supp. 2d 567 (S.D.N.Y. 2008).
43
Id. at 570.
44
NAS FORENSIC SCIENCE REPORT, supra note 2, at 9.
45
Id. at 107-08.
46
The Supreme Court quoted one definition in Daubert: KARL POPPER, CONJECTURES AND
REFUTATIONS: THE GROWTH OF SCIENTIFIC KNOWLEDGE 37 (5th ed. 1989) (“[T]he criterion of the scientific
status of a theory is its falsifiability, or refutability, or testability.”). Daubert, 509 U.S. at 593.
47
The Court wrote: “[I]t would prove difficult, if not impossible, for judges to administer evidentiary
rules under which a gatekeeping obligation depended upon a distinction between ‘scientific’ knowledge
and ‘technical’ or ‘other specialized’ knowledge. There is no clear line that divides the one from the
others.” Kumho Tire, 526 U.S. at 148.
40
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disciplines are ultimately subjective, and there are often no meaningful standards48 —factors that
undercut any claims that these techniques are “scientific.”
“Reasonable Scientific Certainty”
The expression “reasonable scientific certainty,” which is often included (and sometimes
demanded) in expert testimony is another phrase that should be avoided.49 The phrase, which
combines two suspect words— “scientific” and “certainty”—has no scientific meaning.
Although it is used frequently in cases, its legal meaning is ambiguous at best.
Sometimes the phrase seems to be used as a confidence statement (i.e., “I am confident of my
opinion.”), in which case the expert could avoid the term altogether and directly testify how
confident she is in her opinion.50 In some cases, the phrase means something quite different. In
State v. Holt,51 for instance, the expert testified, based on neutron activation analysis, that two
hair samples were “similar and ... likely to be from the same source.”52 The Ohio Supreme Court
ruled that expert testimony is admissible only if the opinion is based upon “reasonable scientific
certainty.” For that court, reasonable scientific certainty meant that the expert had to testify that
the hair sample probably came from the defendant and not that it possibly came from him.53
Holt conflicts with the views other courts and scholars. Experts frequently testify that
two samples “could have come from the same source” or “were likely to be from the same
source.”54 Such testimony meets the relevancy standard of Federal Rule 401, and there is no
requirement in the Federal Rules of Evidence that an expert’s opinion be expressed in terms of
“probabilities.” Thus, in United States v. Cyphers,55 the expert testified that hair samples found
“Often there are no standard protocols governing forensic practice in a given discipline. And,
even when protocols are in place . . . , they often are vague and not enforced in any meaningful way.”
NAS FORENSIC SCIENCE REPORT, supra note 2, at 6.
49
The terms “reasonable medical certainty” and “reasonable ballistic certainty” are similarly
problematic.
50
See James E. Hullverson, Reasonable Degree of Medical Certainty: A Tort et a Travers, 31 ST.
LOUIS U.L.J. 577, 582 (1987) (“[T]here is nevertheless an undercurrent that the expert in federal court
express some basis for both the confidence with which his conclusion is formed, and the probability that
his conclusion is accurate.”).
51
246 N.E.2d 365 (Ohio 1969).
52
Id. at 368.
53
The requirement that experts testify in terms of probability may have originated as a “sufficiency”
rule in civil cases in which causation was an issue. It may then have been improperly converted into an
“admissibility” rule in civil cases and then improperly transplanted into criminal cases. See PAUL C.
GIANNELLI, BALDWIN’S OHIO PRACTICE, EVIDENCE § 702.6 (3d ed. 2010) (describing the Ohio experience
with the term).
54
E.g., People v. Horning, 102 P.3d 228, 236 (Cal. 2004) (expert “opined that both bullets and the
casing could have been fired from the same gun . . . ; because of their condition he could not say for
sure”); Luttrell v. Commonwealth, 952 S.W.2d 216, 218 (Ky. 1997); State v. Reynolds, 297 S.E.2d 532,
539-40 (N.C. 1982). See also State v. Boyer, 406 So. 2d 143, 148 (La. 1981) (reasonable scientific
certainty not required where expert testifies concerning the presence of gunshot residue based on
neutron activation analysis).
55
553 F.2d 1064 (7th Cir. 1977).
48
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on items used in a robbery “could have come” from the defendants.56 The defendants argued
that the testimony was inadmissible because the expert did not express his opinion in terms of
reasonable scientific certainty. The Seventh Circuit responded: “There is no such
requirement.”57
The ambiguity of the term is illustrated in Burke v. Town of Walpole,58 a bite mark
identification case, in which the First Circuit had to interpret the term as used in an arrest
warrant:
[W]e must assume that the magistrate who issued the arrest warrant assigned no more
than the commonly accepted meaning among lawyers and judges to the term “reasonable
degree of scientific certainty”—“a standard requiring a showing that the injury was more
likely than not caused by a particular stimulus, based on the general consensus of
recognized [scientific] thought.” Black’s Law Dictionary 1294 (8th ed. 2004) (defining
“reasonable medical probability,” or “reasonable medical certainty,” as used in tort
actions). That standard, of course, is fully consistent with the probable cause standard.59
In sum, it seems doubtful that a jury would translate “scientific certainty” only as “more probable
than not.”
The phrase has come under attack in recent cases. In United States v. Glynn,60 the court
ruled that the term “reasonable scientific certainty” could not be used in a firearms identification
case. In light of the expert’s admission concerning the subjective nature of the examination, “the
Government did not seriously contest the Court’s conclusions that ballistics lacked the rigor of
science and that, whatever else it might be, its methodology was too subjective to permit
opinions to be stated to ‘a reasonable degree of ballistic certainty.’”61
In 2009, a district court in United States v. Taylor62 wrote: “[B]ecause of the limitations
on the reliability of firearms identification evidence discussed above, Mr. Nichols will not be
permitted to testify that his methodology allows him to reach this conclusion as a matter of
scientific certainty. Mr. Nichols also will not be allowed to testify that he can conclude that
there is a match to the exclusion, either practical or absolute, of all other guns. He may only
testify that, in his opinion, the bullet came from the suspect rifle to within a reasonable degree of
Id. at 1072. See also United States v. Davis, 44 M.J. 13, 16 (C.A.A.F. 1996) (“Evidence was also
admitted that appellant owned sneakers which ‘could have’ made these prints.”).
57
553 F.2d at 1072. See also Boyer, 406 So. 2d at 148 (reasonable scientific certainty not required
where expert testifies concerning the presence of gunshot residue based on neutron activation analysis).
58
405 F.3d 66 (1st Cir. 2005).
59
Id. at 91 (emphasis added).
60
578 F. Supp. 2d 567 (S.D.N.Y. 2008).
61
Id. at 571. In United States v. Willock, 696 F. Supp. 2d 536, 546 (D. Md. 2010), based on a
comprehensive magistrate’s report, held that “Sgt. Ensor shall not opine that it is a ‘practical impossibility’
for a firearm to have fired the cartridges other than the common ‘unknown firearm’ to which Sgt. Ensor
attributes the cartridges.” Thus, “Sgt. Ensor shall state his opinions and conclusions without any
characterization as to the degree of certainty with which he holds them.” Id. at 549.
62
663 F. Supp. 2d 1170 (D. N.M. 2009).
56
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certainty in the firearms examination field.”63
However, replacing the term “reasonable scientific certainty” with the term “reasonable
ballistic certainty” does not solve the problem.64 This phrase suffers from the same defects.
4.
Lab Error, Contamination, and Mishandling
This provision tracks the ABA Standards on DNA Evidence65 and extends it to other
forensic disciplines.
5.
Claims of Uniqueness
Claims of uniqueness must rest on empirically based research. In Daubert, the Supreme
Court quoted philosopher Carl Hempel: “[T]he statements constituting a scientific explanation
must be capable of empirical test.”66 For example, DNA evidence does not claim “uniqueness.”
Although it is generally accepted that every person’s DNA is unique (except identical twins),
current techniques, such as STRs, do not establish that uniqueness. Instead, a random match
probability is presented.
Moreover, the precise claim must be examined. “Even if no two people had identical sets
of fingerprints, this did not establish that no two people could have a single identical print, much
less an identical part of a print.”67 Also, the examiner is comparing impressions of fingerprints,
not friction ridges on fingers. Every time a fingerprint impression is left by a person, it differs in
some respects from other impressions left by that same person. Further, crime scene prints are
typically partial—and distorted due to pressure. Thus, because there frequently are
“dissimilarities” between the crime scene and record prints, the examiner must decide whether
there is a true dissimilarity, in which case there is an exclusion (“no match”), or whether the
dissimilarity is due to distortion or an artifact, in case a “match” is permissible.68 The same issue
arises in other forensic disciplines.
Courts have responded in different ways to claims of uniqueness. Due to a lack of
foundational research, several courts have limited the scope of handwriting testimony, permitting
expert testimony about the similarities and dissimilarities between exemplars but not the specific
63
Id. at 1180.
In addition to the cases cited in the text, the following courts take this approach: Commonwealth
v. Pytou Heang, 942 N.E.2d 927, 945 (Mass. 2011) (“Where a qualified expert has identified sufficient
individual characteristic toolmarks reasonably to offer an opinion that a particular firearm fired a projectile
or cartridge casing recovered as evidence, the expert may offer that opinion to a ‘reasonable degree of
ballistic certainty.’”).
65
DNA EVIDENCE, supra note 5, Standard 16-5.3(d).
66
Daubert, 509 U.S. at 593. CARL HEMPEL, PHILOSOPHY OF NATURAL SCIENCE 49 (1966).
67
Mnookin, supra note 24, at 19.
68
Commonwealth v. Patterson, 840 N.E.2d 12, 17 (Mass. 2005) (“There is a rule of examination,
the ‘one-discrepancy’ rule, that provides that a nonidentification finding should be made if a single
discrepancy exists. However, the examiner has the discretion to ignore a possible discrepancy if he
concludes, based on his experience and the application of various factors, that the discrepancy might
have been caused by distortions of the fingerprint at the time it was made or at the time it was
collected.”).
64
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conclusion that the defendant was the author (“common authorship” opinion).69 Although the
courts have used this approach most frequently in handwriting cases, they have sometimes
applied it to other types of forensic expertise such as firearms examinations.70 One court took a
less restrictive approach, ruling that the expert would be permitted to testify only that it was
“more likely than not” that recovered bullets and cartridge cases came from a particular
weapon.71
“To the Exclusion of All Others”
Experts frequently testify that they have made a match “to the exclusion of all other
firearms.”72 This is simply another way of claiming uniqueness. In United States v. Green,73 the
court questioned such testimony: “O’Shea [the expert] declared that this match could be made
‘to the exclusion of every other firearm in the world.’ . . . That conclusion, needless to say, is
extraordinary, particularly given O’Shea’s data and methods.”74 Further, in 2008, a year before
the NAS report on forensic science was issued, a different NAS report, one on computerized
ballistic imaging, addressed this issue. The report cautioned: “Conclusions drawn in firearms
identification should not be made to imply the presence of a firm statistical basis when none has
been demonstrated.”75 In particular, that report was concerned about testimony cast “in bold
absolutes” such as that a match can be made to the exclusion of all other firearms in the world:
“Such comments cloak an inherently subjective assessment of a match with an extreme
probability statement that has no firm grounding and unrealistically implies an error rate of
zero.”76 Some courts are in accord.77
Individualization. At present, it is easier to identify what an expert should not say than to
prescribe what an expert may legitimately opine at trial. Indeed, some scholars have questioned
whether individualization is even achievable.78 Other scholars do not accept this “radical
skepticism” and believe that such an approach would mislead the jury in the other direction—by
See United States v. Oskowitz, 294 F. Supp. 2d 379, 384 (E.D.N.Y. 2003) (“Many other district
courts have similarly permitted a handwriting expert to analyze a writing sample for the jury without
permitting the expert to offer an opinion on the ultimate question of authorship.”); United States v.
Rutherford, 104 F. Supp. 2d 1190, 1194 (D. Neb. 2000).
70
See United States v. Green, 405 F. Supp. 2d 104, 107 (D. Mass. 2005).
71
United States v. Glynn, 578 F. Supp. 2d 567, 575 (S.D. N.Y. 2008).
72
See 1 PAUL C. GIANNELLI & EDWARD J. IMWINKELRIED, SCIENTIFIC EVIDENCE § 14.01, at 706 n.1 (4th
ed. 2007) (citing FBI HANDBOOK OF FORENSIC SCIENCES 57 (rev. ed. 1994)).
73
United States v. Green, 405 F. Supp. 2d 104 (D. Mass. 2005).
74
Id. at 107 (citations omitted).
75
NATIONAL RESEARCH COUNCIL, NATIONAL ACADEMY OF SCIENCES, BALLISTIC IMAGING 82 (2008).
76
Id.
77
See United States v. Alls, slip opinion, No. CR2-08-223(1) (S.D. Ohio Dec. 7, 2009) (“Although
Ms. McClellan may testify as to her methodology, case work, and observations in regards to the casing
comparison she performed for this case, she may not testify as to her opinion on whether the casings are
attributable to a single firearm to the exclusion of all other firearms.”); Diaz, 2007 WL 485967, at *1.
78
Michael J. Saks & Jonathan J. Koehler, The Individualization Fallacy in Forensic Science
Evidence, 61 VAND. L. REV. 199 (2008).
69
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vitiating the probative value of the evidence.79 This position, however, does not endorse the
overstatements described above. Nor does it minimize the risk of misleading the jury or give the
expert carte blanche authority:
Let us assume that the jury gets the message—a match is not an absolute
identification. Can the criminalist do something more to explain its probative value?
Obviously, this depends on what is known about the frequency of the identifying trait in
the relevant population. Are the features very common, rarely seen, or somewhere in
between? There will be occasions when such qualitative testimony is reasonable. When
no duplicates have been seen after systematic, careful and (one hopes) representative
studies, a criminalist determined to refer to uniqueness might even assert that a trait is
either unique or very rare in a population.80
6.
Declaration of Expertise
ABA Civil Trial Practice Standard 14 provides: “The court should not, in the presence of
the jury, declare that a witness is qualified as an expert or to render an expert opinion and
counsel should not ask the court to do so.”81 This ABA policy should be extended to criminal
cases. As one court has noted,
Great care should be exercised by a trial judge when the determination has been made
that the witness is an expert. If the jury is so informed such a conclusion obviously
enhances the credibility of that witness in the eyes of the jury. All such ruling should be
made outside the hearing of the jury and there should be no declaration that the witness is
an expert.82
In 1994, Judge Richey recommended this approach, noting that such a practice “ensures that trial
courts do not inadvertently put their stamp of authority” on a witness’ opinion, and protects
against the jury’s being “overwhelmed by the so-called ‘experts.’”83
7.
Additional Factors for Consideration in Jury Instructions in Cases Where Forensic
Science Evidence is Contested
The court should consider whether additional factors such as those set forth below might
be especially important to a jury’s ability to fairly assess the reliability of and the weight to be
79
David H. Kaye, Probability, Individualization and Uniqueness in Forensic Science Evidence:
Listening to the Academies, 75 BROOK. REV. 1163, 1185 (2010).
80
Id. at 1180.
81
ABA CIVIL TRIAL PRACTICE STANDARD 14 (2007).
82
Luttrell v. Commonwealth, 952 S.W.2d 216, 218 (Ky.1997). See also United States v. Laurienti,
611 F.3d 530, 547 (9th Cir. 2010) (“To the extent that Defendants argue that the district court abused its
discretion by failing to describe Meyer as an ‘expert’ in front of the jury, we disagree. The determination
that a witness is an expert is not an express imprimatur of special credence; rather, it is simply a decision
that the witness may testify to matters concerning ‘scientific, technical, or other specialized knowledge.’
Fed.R.Evid. 702.”).
83
Charles Richey, Proposals to Eliminate the Prejudicial Effect of the Use of the Word “Expert”
Under the Federal Rules of Evidence in Civil and Criminal Jury Trials, 154 F.R.D. 537, 559 (1994).
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given testimony on particular issues in the case.84
1. The extent to which the particular forensic science technique or theory used in the
analysis is founded on a reliable scientific methodology that gives it the capacity to
accurately analyze evidence and report findings;
2. The extent to which the forensic science examiner followed or did not follow the
prescribed scientific methodology during the examination;
3. The extent to which the particular forensic science technique or theory relies on human
interpretation that could be tainted by error;
4. The extent to which the forensic science examination in this case may have been
influenced by the possibility of bias;
5. The extent to which the forensic science examination in this case uses operational
procedures and conforms to performance standards established by reputable and
knowledgeable scientific organizations;
6. The extent to which the forensic science examiner in this case followed the prescribed
operational procedures and conformed to the prescribed performance standards in
conducting the forensic science examination of the evidence;
7. The qualifications of the person(s) conducting the forensic science examination;
8. Whether he handling and processing of the evidence that was tested was sufficient to
protect against contamination or alteration of the evidence;
9. The extent to which the particular forensic science technique or theory is generally
accepted within the relevant scientific community;
10. The reasons given by the forensic science examiner for the opinion;
11. Whether the forensic science examiner has been certified in the relevant field by a
recognized body that evaluates competency by testing;
12. Whether the facility is accredited by a recognized body if accreditation is appropriate for
that facility;
13. The extent to which the forensic science examiner has complied with applicable ethical
84
The court should instruct the jurors only on the factors relevant to the specific forensic science
evidence in the case as presented by the parties. Not all factors will be relevant in every case. Parties
should consider limiting the instruction to the most probative contested factors to avoid overwhelming the
jury with a “laundry list” of factors that may diminish the jury’s consideration of the most probative
evidence.
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obligations;
14. Whether the physical observations made by the forensic science examiner are observable
by others;
15. Other evidence of the accuracy of the forensic science examiner’s conclusions;
16. The extent to which the forensic science technique or theory has undergone validation;
17. The known nature of error associated with the forensic science technique or theory;
18. The fact that the nature and degree of error associated with the forensic science technique
or theory (why and how often incorrect results are obtained) cannot or has not been
determined;
19. The estimation of uncertainty (the range of values encompassing the correct value at a
defined confidence interval) associated with the forensic science technique or theory.
Courts have the responsibility to ensure jurors understand the law they are to apply, the
issues they will be asked to determine, and the factors they may properly consider in determining
those issues. The goals of jury instructions are to increase the legal accuracy of verdicts, and
thereby avoid reversals, and to improve juror comprehension of presented evidence.
Unfortunately, jury instructions are frequently written in complicated legal terminology
that is not readily accessible to jurors. Pattern jury instructions, while reducing reversals by
using language from appellate opinions setting legal standards, do not necessarily track the
specific issues of the case and do not improve juror comprehension or help them to properly
assess the weight of the evidence. This is particularly true with forensic science evidence. Few
pattern jury instructions address the factors jurors may use in determining the weight of the
evidence or guide jurors on the proper use of evidence concerning the reliability of forensic
science examinations. Instructions should be provided to jurors that are tailored to the facts of
each individual case and where forensic science evidence is contested, the instructions should
reflect the evidence presented and the factors affecting the reliability of the evidence.
Preliminary instructions should be used to provide guidance on the contested forensic science
issues to improve juror comprehension. See Principle 6 C, ABA Principles for Juries and Jury
Trials, 2005.85 The above list of additional factors identifies many of the considerations that
jurors should consider in evaluating contested forensic science evidence presented at trial.
Respectfully submitted,
Janet Levine
Chair, Criminal Justice Section
February 2012
85
These instructions should be given in addition to the standard jury instructions explaining the
difference between lay witnesses and witnesses who are permitted to give opinion, without vouching for
the witnesses by having the court designated them as “experts.”
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GENERAL INFORMATION FORM
Submitting Entity:
Criminal Justice Section
Submitted By:
Janet Levine, Chair
1.
Summary of Resolution(s). The resolution urges judges who have decided to admit expert
forensic science testimony to consider a number of factors in determining the manner in
which that evidence should be presented to the jury and how to instruct the jury in its
evaluation of scientific testimony in criminal and delinquency proceedings.
2.
Approval by Submitting Entity. The resolution was approved by the Criminal Justice
Section at its October 29, 2012 Fall meeting.
3.
Has this or a similar resolution been submitted to the House or Board previously? Many of
the factors that the pending resolution asks judges to consider in determining the
admissibility of forensic evidence are contained in Standard 5.3 (Presentation of Expert
Testimony) of the ABA Criminal Justice Standards on DNA Evidence (approved 2006
Annual Meeting). For example, the DNA Standards have the same or similar requirements
as the current proposal’s subsections --- 1, 3, 4, and 5. The requirement in subsection 2 that
experts use clear and consistent terminology in presenting their opinions drew from
Resolution 100E(4) (2010 Annual Meeting) which urged federal funding to, inter alia,
“facilitate the development and adoption of standards and common terminology for the clear
communication of scientific testing results.
4.
What existing Association policies are relevant to this Resolution and how would they be
affected by its adoption? The DNA Standards noted above are relevant, and some of the
factors contained in those Standards would be extended here to include non-DNA-related
forensic evidence. The resolution’s call for common terminology which is consistent with
Resolution 100E(4).
5.
What urgency exists which requires action at this meeting of the House? The 2009
National Academy of Sciences report, Strengthening Forensic Science in the United States:
A Path Forward mentions difficulties with jurors’ understanding and correctly interpreting
forensic science evidence, which can sometimes caused by misleading presentation and
instructions. The NAS Report suggests model jury instructions as a way to facilitate jury
decision-making. Concerns about the presentation of forensic science evidence have
also recently appeared in the Supreme Court’s Confrontation Clause jurisprudence, and
have been an issue in some cases where defendants were wrongfully convicted. Currently,
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there is little, if any, guidance about the presentation of forensic science evidence at trial after
judges have determined its admissibility, or factors to be considered in jury instructions. Use
of the listed factors will enhance jurors’ understanding of such evidence, and facilitate
reasoned decisions.
6.
Status of Legislation. (If applicable).
7.
Brief explanation regarding plans for implementation of the policy, if adopted by the House
of Delegates.
The resolution and report will be distributed to organizations of judges and lawyers, as well
as forensic science organizations. CLE and media outreach is also contemplated concerning
and this resolution and the related voir dire and discovery issues in the other forensic science
resolutions being currently proposed.
8.
Cost to the Association. (Both direct and indirect costs) --- No cost to the Association is
anticipated.
9.
Disclosure of Interest. (If applicable) None.
10. Referrals. Concurrently with the submission of this resolution to the ABA Policy
Administration Office for calendaring on the House of Delegates agenda for the
2012 Midyear Meeting, it is being circulated to the chair (or president) and staff
director (or executive director) of the following ABA entities and outside organizations:
Standing Committees
Antitrust Law
Ethics and Professional Responsibility
General Practice, Solo and Small Firm Division
Governmental Affairs
Gun Violence
Legal Aid and Indigent Defense
Substance Abuse
Special Committees and Commissions
American Jury Project
Bioethics and the Law
Death Penalty Representation Project
Domestic and Sexual Violence
Coalition on Racial and Ethnic Justice
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Sections and Divisions
Government and Public Sector Lawyers
Individual Rights and Responsibilities
Judicial Division
Litigation
National Conference of Federal Trial Judges
National Conference of State Trial Judges
National Conference of Specialized Court Judges
Science and Technology Law
State and Local Government Law
Taxation
Young Lawyers Division
11. Contact Name and Address Information. (Prior to the meeting).
Professor Myrna Raeder
Southwestern Law School
3050 Wilshire Boulevard
Los Angeles CA 90010
PH: 213/738-6775
Cell: 310/770-8111
Email: mraeder@swlaw.edu
Professor Paul Giannelli
Case Western University Law School
11075 East Boulevard
Cleveland OH 44106
PH: 216/368-2098
E-mail: paul.giannelli@case.edu
12. Contact Name and Address Information. (Who will present the report to the House)?
Stephen A. Saltzburg, Section Delegate
George Washington University Law School
2000 H Street NW
Washington DC 20052-0026
PH: 202/994-7089; 202 /489-7464 (cell)
E-mail: ssaltz@law.gwu.edu
William N. Shepherd, Section Delegate
Holland & Knight LLP
Suite 1000
222 Lakeview Ave
West Palm Beach, FL 33401-6148
PH: 561/650-8338; 561/723-9669 (cell)
E-mail: William.shepherd@hklaw.com
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EXECUTIVE SUMMARY
1.
Summary of the Resolution
This resolution urges judges who have decided to admit expert testimony to consider a
number of factors in determining the manner in which that evidence should be presented
to the jury and how to instruct the jury in its evaluation of expert scientific testimony in
criminal and delinquency proceedings.
2.
Summary of the Issue that the Resolution Addresses
While forensic scientific evidence can be extremely valuable, it can be difficult for lay
jurors to understand and weigh its relevance to the case before them. It is important,
therefore, that the experts who present it will do so in a manner that accurately and fairly
conveys its significance and the significance of their conclusions. In addition, jury
instructions can help focus the jurors on the relevant forensic science issues.
3.
Please Explain How the Proposed Policy Position Will Address the Issue
The proposed policy will provide judges a checklist of questions to consider in assessing
how experts should present contested forensic science evidence, and the nature of jury
instructions that should be given to jurors.
4.
Summary of Minority Views
None known.
17